There are 31 pairs of nerves coming out of either side of the spinal cord and any one of them can be affected. Red spots turn into painful blisters and are confined to one nerve on one side of the body.

The blisters burst and scab, lasting between one and three weeks. Once the scabs fall off, the scars can last for weeks. However, the pain lasts for months, maybe as long as two years. It is what doctors call intractable pain, very resistant to painkillers.

Although shingles can affect every age group, it is worst in the elderly. But adults with shingles can give chickenpox to children who have not had the disease since the virus is active in the blisters, which are infectious until they have dried and healed.

The most serious sort is herpes opthalmicus, involving the eye nerve. This can spread from one half of the forehead and cause an ulcer on the cornea. This type of shingles needs the supervision not only of your GP, but also of a consultant opthalmic surgeon to prevent scarring which could affect your vision.

Teacher: MichaelMany articles taken from 'A word with the doctor', by Dr. John Windsor.